Air intake control apparatus



1959 H. B. c. DHONAU ETAL 2,870,955

AIR INTAKE CONTROL APPARATUS Filed June 18, 1956 4 Sheets-Sheet 1 v 5 I IN VENTORS.

5 $022!? 5/7630 fig WW Jan. 27, 1959 Filed June 18, 1956 H. B. C. DHONAU ET AL AIR INTAKE CONTROL APPARATUS 4 Sheets-Sheet 2 INVENTORJ'.

A ORA E Y 1959 H. B. c. DHONAU ETAL 2,370,956 A AIR INTAKE CONTROL APPARATUS Filed June 18, 1956 4 Sheets-Sheet 3 I IN VENTORJ! Jim/m8 Mia/m q By 5 flaw/677511022- 2" TTORNEK Jan. 27, 1959 H. B. c. DHONAU ET AL 2,

AIR INT KE CONTROL APPARATUS Filed June 18, 1956 4 Sheets-Sheet 4 'Herman B.C. Dhonau andfStan'ley E. Nelson, Indianapolis, Ind, assignorsto General Motors Corporation, Detroit,.Mich., a corporation of Delaware Application June 18, 1956, Serial No. 591,986 l-Claim. (Cl. 230-414) This invention relates to air intake control apparatus and more particularlyto air intake control. apparatus for gas turbine power plants.

One of the problems encountered in axial flow compressors of gas turbine power plants is compressor surge which occurs during acceleration of the power plant. This surge ordinarily occurs when the axial velocity of the air flow in the initial stages of the compressor is low while the axial velocity of the air flow in later stages of the compressor is high. Various arrangements have been proposed to prevent this compressor surge. One arrangement bleeds air from an intermediate compressor stage in order to increase the air flow in the initial compressor stages with respect to the air flow in the later compressor stages. Another arrangement employs variable compressor inlet guide vanes whichare mounted in the forward portion of the compressor frame to alter the ratio of the compressor inlet area to the compressor outlet area. The present invention is directed toward the problem of compressor surge and. compensates for this surge by reducing the inlet area ofthe compressor through the use of blockage flaps which are movable between a normal position flush with one of the. annular walls of the com-- pressor forward frame and a blocking position obliquely and rearwardly outwardly extending with respect to the wall wherein the flaps reduce the effective area of the compresso-r inlet. By reducing the effective area ofthe compressor inlet, the ratio of the compressor inlet area to the compressor outlet, area is changedand the compressor surge is thereby prevented.

The primary object ofthis invention is to provide a new and improved air intake control apparatus. Another object of this invention is to provide a new and improved air intake control apparatus for A further object of this invention is to provide; a new and improved air intake control apparatus for gas turbine power plant compressors which. is operable to alter the ratio of the compressor inlet area to the compressor outlet area to prevent compressor surge. Yet, another ob .ject of this inventiongis to provide a new and improved air intake control apparatus for gas turbine power plant compressors which includes a number of flaps movable between a normal position and ablocking position wherein the flaps, reduce the effective inlet area of the compressor to thereby alter the ratio between the compressor inlet area and the compressor outletarea and prevent compressor surge;

These and otherobjects of'this invention will be readily apparent from the following specification and drawings,

in which:

Figure 1 is a partial front elevational view of the forward frame of a gas turbinepower plant. compressor embodying an air intake control apparatus according to this invention, with parts thereof being broken away. at segmentsA, B, C, and D corresponding to partial axial sectional views indicated at segment AA and segment BB of Figure 4 and segment C -C and segment D-- D ofFigure 2;

gas turbine power plants.

United States Patent 2,870,955 Fatented Jan. 27, 1959 Figure 2 is a partial sectional view taken on the plane indicated by line 2-2 of Figure 1 and showing the blocking flaps in blocking position;

Figure 3 is a partial sectional view taken on the plane indicated by line 3-3 of Figure 1;

Figure 4 is a partial sectional view taken on the plane indicated by line 44 of Figure, l;

Figure 5 is a sectional view taken onthe plane indicated by line 55 of Figure 1;

Figure 6 is a partial front elevational view of the forward frame of a gas turbine power plant compressor embodying a modified air intake control apparatus according to this invention, with parts thereof broken away for clarity of illustration; and

Figure 7 is a sectional view taken on the plane indicated by line 7-7 of Figure 6.

Referring now to Figure 1 of the drawings, the forward frame of an axial flow compressor of a gas turbine power plant includes .an outer annular wall 10 and an inner annular wall 12 which are joined by four radially extending struts .14. An annular row of entrance guide vanes 16 is, located within the forward frame rearwardly of struts 14 as shown particularly in Figure 2. The entraneeguide vanes have their radially outer ends located by an outer annular shroud 18 and their radially inner ends located by. a similar inner annular inner shroud 2! with both of the shrouds being mounted on the forward frame of the compressor. The entrance guide vanes impart an initial swirl to the air entering the compressor and are fixed in position although they may be variably as is wellknown. h

The inner and outer annular walls and struts 14 of the forward frame define four annular segmental air flow orifices to the compressor. Under normal power plant operating conditions no barrier is interposed to the flow of ambient air through these segmental orifices to the compressor. However, under certain power plant acceleration conditions, compressor surge takes place. In order to prevent this surge, this invention provides an air intakecontrol apparatus which includes blockage flaps movable between a normal position flush with the inner annular wall 12 of the frame, as shown schematically in Figure 2, and a blocking position obliquely and rearwardly outwardly extending with respect thereto, as shown in Figures 1 through 5, wherein the flaps reduce the efiective compressor inlet area to thereby alter the ratio between the compressor inlet area and the compressor outlet area. The blockage flaps are divided into four quadrants of five flaps each, and are power operated for movement between normal and blocking position. Since all of the quadrants are of the same construction, only one will be particularly described.

Referring now particularly to Figure 2 of the drawings, the inner wall 12 of the compressor frame is cut away intermediate each pair of struts 14 to provide an annular opening 22. A ringseg ment 24 is positioned radiallyinwardlyof wall 12 and includes spaced annular walls joined by a number of intermediate annular bosses. Preferably the spaced annular walls and the annular bosses of ring segment 24 are formed integral with each other although they may be formed otherwise. Five lugs 30 are provided with threaded extensions 32 which extend through five alternately located intermediate bosses 34 of ring'segment24 andare secured to the bosses by nuts 36.

Each of the five'blockage flaps 38 of each quadrantis 48"which is pivoted therein at 50, Lug 48 is provided with a threaded extension 52 which extends radially and axially inwardly through the inner radially and obliquely extending wall 54 of a U-shaped housing 56 and is secured thereto by means of a nut 58. t

The U-shaped housings 56 are equally spaced with respect to each other within each of the quadrants and project radially inwardly with respect to the inner annutinuous radially and obliquely extending annular wall 62.

Circumferentially extending annular wall segments 63,. Figures 4 and 5, extend between the adjacent side walls of each housing 56 and merge into radially extending annular wall segments 64, Figures 4 and 5, which also join the adjacent side walls of housings 56 and are joined to the axially inner end of the annular wall 60. In the area of struts 14, as can be seen in Figure 1, wall segments 63 and 64 are of greater extent than between the housings 56 of each quadrant. A pair of annular bosses 65, Figures 1 and 4, extend between the annular wall 64 and the outer radially inwardly extending continuous flange 66 of the inner wall 12 within each of the quadrants.

Referring now to Figures 3 and 4, the bosses are 7 provided with an axial bore 68 which opens through flange 66. A sleeve 72 is mounted within each of the bores 68 and provided with laterally extending flanges 74, as shown inFigures l and 3, which bear against flange 66 to either side of bore 68. Sleeve 72 includes bore portions 76 and 78 of substantially the same diameter, and an intermediate bore portion 80 of a lesser diameter than bore portions 76 and 78 and defining an annular inwardly extending rib81. A piston and piston rod assembly 82 is slidably mounted within bore portions 76, 78, and 80 of each sleeve 72. The inner piston rod 84 of assembly 82 has a threaded end of reduced diameter which is received Within an annular boss 85 of ring segment 24 and is secured to the ring segment by a nut 86. An annular sealing ring 88 fits within the bore portion 78 of sleeve 72 around piston rod 84 and is retained therein by a split ring 90. Assembly 82 also includes a piston 92 of a diameter slightly less than the diameter of bore portion 76 and an outer piston rod 94. An O-ring 96 fits within an annular groove in the outer surface of piston 92 and is compressed between the piston and the Wall of bore portion 76 to provide a seal. Piston rod 94 is provided with a central bore 98 opening to the outer end thereof and opening at its inner end to an angularly extending bore 100 which opens to the inner side of piston 92 as shown in Figure 4. v

A pressure fluid inlet member includes a sleeve 102 and flanges 104 extending laterally from the sleeve adjacent the inner end thereofand being of the same extent as flanges 74 of sleeve 72. Flanges 74 and 104 are provided with aligned openings and bolts 106 extend through these openings and are threaded into threaded bores 108 in the outer flange 66 to mount the fluid inlet member and sleeve 72 on flange 66 of the inner wall 12 of the compressor frame. A threaded coupling 110 is threaded in the end of sleeve 102 and a similar threaded coupling 112 is threaded within an annular boss 114 of the fluid inlet member which includes a passage 116 connecting the bore of boss 114 with sleeve 102. The sleeve extends partially inwardly within bore portion 76 of sleeve 72, and an O-ring 118 mounted within an annular groove of sleeve 102 provides a seal between the sleeves.

Referring now particularly to Figure 5 of the drawings, a pair of guide rods 122 extend through aligned openings 124 and 126 in the outer flange 66 and wall 62, respectively, with the inner end of each guide rodbeing received within a bore 128 provided in an enlarged portion of two of the wall segments 64. O-rings 130 and, 132 are mounted within annular grooves of each guide rod 122 within openings 124 and 126, respectively, to provide a seal. The guide rods are slidably received within two spaced annular bosses 134 of ring segment 24 and provide 'both a support and a guide for the ring segment at two spaced portions thereof to either side of the mounting of the center flap 38 of each quadrant on the ring segment. .A split ring 135 fitting within opening 124 of flange 66 :retains the guide rod 122 in place with its inner end thereof engaging the base of bore 128.

As previously mentioned, the blockage flaps 38 within each of the quadrants are power operated for movement between a normal position wherein the flaps are substantially flush with the inner annular wall 12 of the compressor forward frame as shown schematically in Figure 2, and a blocking position as shown in Figures 1 through 5, wherein the flaps are positioned obliquely and :rearwardly outwardly extending with respect to the inner annular wall 12 so as to reduce the effective compressor :inlet area. The piston and pistonrod assemblies 82 and sleeves 72 provide a pair of power operated units for each quadrant to move the ring segments 24 of the quadrant axially inwardly and outwardly with respect to wall 12 to move the blockage flaps 38 between normal and blocking positions. The assemblies 82 also aid the guide rods 122 in supporting the ringsegment .24 in spaced radial relationship with wall 12 and guiding the axial movement of the ring segment with respect to the wall 12. It will be noted upon reference to Figures 1 through 5 that the :flaps only'partially close the annular segmental orifices 'when in blocking position. In the arrangement shown in the drawings, the blockage flaps reduce the effective compressor inlet area approximately 20% when in block- :ing position, although the effective area may be reduced to a greater orlesser extent as desired.

Referring now particularly to Figures 2 and 4 of the drawings, when the blockage flaps 38 are in blocking position, the ring segment 24 of each quadrant is positioned inwardly of opening 22 adjacent the annular wall segments 64, and the pistons 92 of each assembly 82 are positioned at the inner end of bore portion 76 of sleeve 72 adjacent rib 81. When ring segments 24 and pistons 92 are in these positions, coupling 110 is connected to exhaust and pressure fluid is continually admitted through couplings 112 to pass through passage 116 into the annular space 'between piston rod 94 and the wall of bore portion 76. Since the blockage flaps receive the thrust of the entering ambient air when in blocking position, the pressure fluid must be continually admitted through coupling 112 to hold the fiaps in this position. The O-ring 96 and the sealing ring 88 cooperate to insure that none of the pressure fluid will pass along the inner piston rod 84 and then drip into the entering ambient air.

When the blockage flaps are moved to blocking position, the movement of each ring segment 24 axially inwardly with respect to the inner wall 12 moves the pivots 42' axially inwardly to thereby move'the flaps to their blocking position as links 44 swing radially outwardly about pivots 50. Upon reference to Figure 1, it will be noted that the guide rods 122 of each quadrant are located immediately adjacent the terminal bosses 34 of the ring segment 24 which support the terminal flaps 38 and that the piston and piston rod assemblies 82 of each quadrant are located to either side ofthe center boss 34 which supports the center flap 38 of the quadrant. The terminal flaps 38 of each quadrant are partially cut away at to provide clearance between the flaps and the struts 14 which join the inner and outer annular walls 12 and 10, respectively, of the forward'frame.

When it is desired to move the blockage fiaps from blocking position, as shown in Figures 1 through 5, .to normal position, as indicated schematically in Figure 2, wherein the flaps of each quadrant fit within the annular opening 22 in the inner wall, pressure fluid is admitted through coupling 110 and coupling 112 is connected to exhaustl The pressure fluid admitted through coupling 110 passes into sleeve 102 and then into the bore 98 of the outer piston rod 94. The fluid then passes through the angularly extending bore 100 to the inner side of piston 92 between the piston and the adjacent annular wall of the annularly extending rib 81. Pistons 92 will then move outwardly within bore portions 76 of sleeve 72 to move ring segment 24 axially outwardly with respect to the inner annular wall 12 of the forward frame. This will shift pivots 42 axially outwardly so as to move the blockage flaps 38 to their normal position within opening 22 as links 44 swing radially inwardly about pivots 50. Each of the blockage flaps 38 is of curved cross section so as to continue the curvature of the inner annular wall 12 in the area of opening 22 when the block age flaps are innormal position. It should be noted that the blockage flaps fay also be moved to an intermediate position between normal and blocking positions so as to reduce the effective compressor inlet area to a lesser extent if so desired.

Referring now particularly to Figures 6 and 7 of the drawings, a modified air intake control apparatus is shown therein. This modified apparatus is substantially the same as that shown in Figures 1 through 5 of the drawings, except that the guide rods 122 and piston and piston rod assemblies 82 have now been combined into single units rather than being independent units.

The bosses 65 which extend between the continuous annular Wall 62 and the outer flange 66 of the inner annular wall 12 are now located immediately adjacent the terminal flaps 38 of each of the quadrants. The sleeve 72 and the piston and piston rod assembly 82 fit within the bore 68 of each of the bosses, and the inner piston rod 84 of assembly 82 extends through the ring segment 24 and into a bore 142 provided in walls 63 and 64 which have been thickened between two of the U- shaped housings 56 as shown in Figure 7. The inner piston rod 84 is provided with a threaded portion 146 and a nut 148 threaded on portion 146 bears against the inner face of ring segment 24 to hold the ring segment against a split ring 150 which fits within an annular groove of piston rod 84.

The guide rods 122, assuch, are thus not used in the modified assembly since the inner piston rod 84 functions as both the actuating and the guiding member for the ring segment. The operation of the modified control apparatus is substantially the same as the apparatus blockage flaps are power operated for movement between normal and blocking positions so as to hold the flaps in either position without shifting or other movement thereof. A safety feature is also provided in the operation of the blockage flaps in the event of failure of the hydraulic system of the engine. Since the blockage flaps receive the full thrust of the incoming ambient air when in blocking position, failure of the hydraulic power system of the engine Will result in the blockage flaps being moved to a normal position by the thrust of the incoming air. Thus, the pilot need not worry about operation of the blockage flaps in the event of failure of the hydraulic system of the engine.

It is intended that each of the couplings 110 for each of the quadrants of blockage flaps and also the couplings 112 be interconnected by suitable pressure fluid manifolds to provide for simultaneous operation of each of the quadrants of flaps between normal and blocking positions or to any position therebetween. Thus, a single control member located in the pilots compartment may be used to simultaneously operate all of the blockage flaps in unison to the desired position.

We claim:

In an air intake for a gas compressor having an inner annular wall and an outer annular wall forming an annular air flow orifice therebetween, blockage means for reducing the area of said orifice including a plurality of circumferentially arranged ring segments adjacent one 01 said walls, a plurality of guide members carried by said one Wall slidably mounting said segments for axial movement thereon, a plurality of operating members carried by said one wall each operatively connected to shown in Figures 1 through 5, except that the inner piston rod 84 now moves inwardly and outwardly within bore 142 as the blockage flaps 38 move between blocking and normal positions, respectively.

Thus, this invention provides an air intake control apparatus for gas turbine power plants which is operable to alter the ratio of the compressor inlet area to the compressor outlet area to prevent compressor surge. The blockage flaps are disposed in an out-of-the-way position flush with the inner annular wall of the compressor forward frame when in normal position so as not to interpose any barrier to the inward flow of ambient air through the spaced annular segmental orifices. The

one of said segments for axially moving said segments relative to said one wall, a plurality of circumferentially arranged links pivoted at one end to said one wall, a plurality of blockage flaps circumferentially arranged and each pivotally supported on the other end of one of said links, and each of said flaps pivotally connected to one of said ring segments for causing swinging movement of said flaps between a position substantially parallel to said one wall to a position oblique to said one wall and ex tending toward the other of said walls, "when said segments are axially moved on said guide members by said operating members.

References Cited in the file of this patent UNITED STATES PATENTS 2,455,251 Hersey Nov.30, 1948 2,689,680 Lovesey Sept. 21, 1954 FOREIGN PATENTS 30,289 France Dec. 21, 1925 (Addition to No. 600,436)

260,995 Italy Oct. 25, 1928 702,266 Great Britain Jan. 13, 1954 951,944 France Apr. 25, 1949 966,975 France Mar. 15, 1950 1,010,604 France Mar. 26, 1952 

